Focal plane shutter control mechanism for a photographic shutter

ABSTRACT

A focal plane shutter control mechanism wherein means are provided for equlizing the inertias of the front and rear screens and their associated drive mechanisms so as to eliminate uneven exposures. A transmission means for driving first and second wind-up gears associated respectively with the front and rear screens is disengaged and a cam member is actuated by over-driven bias means to compensate for the overlap of the front and rear screens in their cocked positions.

United States Patent 1 1 [111 3,739,704

, Akiyama June 19, 1973 [54] FOCAL PLANE SHUTTER CONTROL 9 3,138,0836/1964 Thomas et al. 95/57 MECHANISM 1 011 A PHOTOGRAPHIC 3,289,56112/1966 3,498,195 3/1970 SHU I 3,572,231 3/1971 [75] Inventor:KazuliiroKliiyamaQSaitama, Japan [73] Assignee: Minolta Camera KabushikiKaisha,

Primary ExaminerSamuel S. Matthews Osaka-sh! Osaka-fl! Japan AssistantExaminer-E. M. Hero 22] I Filed: Nov. 8, 1971 Attorney-Watson, Cole,Grindle & Watson [2l] I App]. No.: 196,353

301 Foreign Application Priority Data 57 ABSTRACT Nov. 9, 1970 Japan45/97854 Nov. 1311976 japanilff.QI ILITIIQHI ZS/H2516 A focal planeshutter control mechanism wherein means are provided for equlizing theinertias of the [52] US. Cl. 95/57, 95/53 front and rear screens andtheir associated drive mech- [Sl] Int. Cl. G03b 9/28 anisms so as toeliminate uneven exposures. A trans [58] Field of Search 95/57, 53mission means for driving first and second wind-up Q g I I I gearsassociated respectively with the front and rear [56 References Citedscreens is disengaged and a cam member is actuated by UNITED STATESPATENTS over-driven'bias means to compensate for the'ov'erlap 2 407 2779,1946 incline 7 95,57 of the front and rear screens in their cockedpositions.

9 t I I n s s A v s u r 4 s s s s s s s u n u I 4 I I s I I n 14 Claims,1.4 Drawing Figures Patented June 19, 1973 3,739,704

4 Sheets-$heet 1 Patented June 19, 1973 4 Sheets-Sheet 2 Patented June19, 1973 3,739,704

4 Sheets-Sheet 5 Patented June 19, 1973 4 Sheets-Sheet 4 vim-ma FIG. 90

F I G. 8 laaf loe 'u 112 IT!) FIG. 9c

WWI/A FOCAL PLANE SHUTTER CONTROL MECHANISM FOR A PHOTOGRAPHIC SHUTTERBACKGROUND OF THE INVENTION The present invention relates to a focalplane shutter mechanism for a photographic camera, and more particularlyto a focal plane shutter mechanism for a photographic camera adapted toeffect the exposure by adjusting the time when a front screen and a rearscreen are released.

In such a kind of focal plane shutter mechanism for a photographiccamera, in order to obtain an exposure suitable for a photosensitivefilm from the deviation of the starting time of both screens and holdsuch deviation uniform, it is necessary to equalize the driving force onthe front screen side at the time when the front screen is released andequalize the inertia of a member driven together with the front screenwith the driving force on the rear screen side and equalize the inertiaof a member driven together with the rear screen.

Thereupon, in the present invention both inertias are equalized and thestarting position of the rear edge of front screen coincides with thestarting position of the front edge of closing screen.

In this respect, in the prior focal plane shutter mechanisms for aphotographic camera a driving gear for cocking the shutter and a firstwind-up gear for driving a first wind-up shaft to cock the front screenand a second wind-up gear for driving a second wind-up shaft to cock therear screen are meshed at least until the shutter is'released,Therefore, the overlap given to the rear edge of the front screen andthe front edge of the rear screen so as to prevent light leakage whenthe shutter is cocked is out of the starting position of the rear edgeof the front screen and the starting position of the front edge of therear screen. Also, the inertia of a member driven together with thefront screen is different from the inertia of a member driven togetherwith the rear screen, so that an uneven exposure is effected when theshutter is released.

In addition, in the prior focal plane shutter mechanism for photographiccameras the driving energy for driving both shutter screens depends onlyupon springs respectively built in winding cylinders for taking up theshutter screen, therefore, the initial running speed of both screens isnot increased rapidly.

OBJECT OF THE INVENTION One object of the present invention is toprovide a focal plane shutter mechanism for a photographic camera inwhich a winding gear group for cocking the shutter breaks off theconnection with the first and second wind-up shafts and returns thewinding gear group at the termination of shutter cocking.

Another object of the present invention is to provide a focal planeshutter mechanism for a photographic camera which enables the startingposition of the rear edge of the front screen coincide with the startingposition of the front edge of the rear screen when the front and rearscreens are released from the cocked position.

' Further another object of thepresent invention is to provide a focalplane shutter mechanism for a photographic camera in which springsprovided respectively on a first wind-up gear and a second wind-up gearengage respectively with a first wind-up shaft and a second wind-upshaft to cock the shutter, and the springs provide give the returningrotation force respectively to the first and second wind-up gears andbreak off the connection with the first and second wind-up shaftssimultaneously with termination of shutter cocking, and decrease theintertias of the members driven together with the front and rear screensrespectively by the driving members when the shutter is released and atthe same time equalize both inertias.

Still further another object of the present invention is to provide afocal plane mechanism for a photographic camera in which spring meansfor returning the first and second wind-up gears provides an initialdriving torque to the respective first and second wind-up shafts whenthe shutter is released.

SUMMARY OF THE INVENTION In order to attain the above-mentioned objects,the present invention provides a first wind-up gear for cocking thefocal plane shutter mechanism for a photographic camera having atoothless portion and interlocked with a transmission gear meshing witha first wind-up gear engaged with a first wind-up shaft for cocking thefront screen via a first interlocking member and given a returningtendency by a spring and a second wind-up gear engaged with a secondwind-up shaft for cocking the rear screen and given a returning tendencyby a spring. At the termination of shutter cocking after a restrainingmember restrains the first and second wind-up shafts at the cockedpositions. The interlocking between the cocking gear and the first andsecond wind-up gears is broken by the toothless portion of the cockinggear, and the first and second wind-up gears are returned to rotate soas to break off the engagement of the first and second interlockingmembers on the first and second wind-up gears with said the first andsecond wind-up shafts.

The focal plane shutter mechanism for a photographic camera formed asdescribed above in accordance with the present invention has thefollowing features:

l. The inertias of the interlocking movable systems driven by drivingmembers on the front screen side and on the rear screen side arerespectively decreased and equalized with each other. As a result, thescreen movement is stabilized and it is possible to obtain a sufficientoverlap between both screens when cocked and enables the startingpositions of both screens to coincide with each other so as to effect aneven exposure.

2. It is possible to permit the interlocking systems on the front screenside and on the rear screen side to move independently by means ofinterlocking members for engaging with and disengaging from the firstand second wind-up shafts provided on first and second wind-up gearshaving a returning tendency and thereby increase the initial runningspeed of the front and rear screens and stabilize the running thereof.

3. Both the first and second wind-up gears are rotated to return bymaking the interlocking members for the first and second wind-up gearsrespectively spring means and to provide an initial driving torquerespectively to the first and second wind-up shafts when the shutter isreleased, to improve the acceleration thereof and weaken the tensiongiven to both screens as well.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing theformation of the essential portion of an embodiment in accordance withthe present invention.

FIG. 2 is a plan view showing the relative disposition of the windinggear, first and second wind-up gears, and the first and second wind-upshafts just prior to termination of shutter cocking in the embodiment ofFIG. 1.

FIGS. 3a and 3b are plan views showing the relationship between therestraining plate of both wind-up shafts and the restraining member atthat time, wherein FIG. 3a shows the first wind-up shaft and FIG. 3bshows the second wind-up shaft.

FIG. 4 is a plan view showing the relative disposition of the windinggear, the first and second wind-up gears as they are rotated to return,and the first and second wind-up shafts after termination of shuttercocking in the embodiment of FIG. 1. FIGS. 5a and 5b are plan viewsshowing the relationship between the restraining plate of both wind-upshafts and the restraining member at that time, wherein FIG. 5a showsthe first windup shaft and 5b shows the second wind-up shaft.

FIG. 6 is a plan view showing the relative disposition of the first andsecond wind-up shafts at the termination of returning in FIG. 4.

FIG. 7 is a plan view showing the relative disposition of the first andsecond wind-up shafts at the termination of shutter release.

FIG. 8 is a plan view showing the formation of the essential portion ofanother embodiment in accordance with the present invention.

FIGS. 9a-9c are partial side views in section for illustrating theoperation of the first wind-up shaft of the second embodiment, whereinFIG. 9a shows the state just prior to the termination of cocking, FIG.9b shows the state the wind-up gear is returned through about one round,FIG. 9c shows the state the wind-up gear is returned through about tworounds, and FIG. 9d shows the state when the running of the shutterscreen is terminated.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the first embodiment shown inFIG. 1 through FIG. 7 in accordance with the present invention windinggear 1 fixed to a winding lever not shown in the drawings is providedwith toothless portion la which breaks off the connection at the meshingposition with a connection gear for meshing with winding shutter rockinggear 1 just after termination of winding.

' Connection gear 2 is pivoted rotatably on fixed shaft 3 on the baseplate of a camera body, and on the top surface of connection gear 2 pin2a is fixed, and onto pin 2a is supported one end 4a of return spring 4,the other end of which is fixed to fixed shaft 3.

Front screen gear 5 and rear screen gear 13 are meshed with connectiongear 2 as shown in the drawings and fitted respectively on front andrear screen bearing rings 7 and 15 fixed on the base plate. Drivingplates 6 and Marc respectively fixed on gears 5 and 13 and on theprojection pieces of plates 6 and 14 driving pins 6a and 14a arerespectively provided.

On the peripheries of bearing rings 7 and 15 springs 8 and 16 arerespectively fitted one ends of which are respectively fixed to bearingrings 7 and 15 and the other free ends of which engage respectively withdriving pins 6a and 14a and also sngage respectively with first andsecond wind-up shaft pins a and 18a mounted respectively on front screendisk 10 and rear screen disk 18 so as to cooperate with each other.

The upper ends 9a and 17a of first and second windup shafts 9 and 17 aresupported respectively on the base plates of the camera body and thelower ends 9a and 17b thereof are respectively fitted in bearing rings 7and 15. Front screen cylinders 10 and 10 and front screen restrainingplate 11 are fixed to first wind-up shaft 9 and circumferential edgefront screen ribbon A is pasted thereto.

Front screen restraining plate 11 is provided with notched portion 1 1aand supported by a pin on the base plate of the camera body andengageable with front screen restraining pawl 12 rotatable ininterlocking with the shutter release. And, just before shutter cockingis terminated there is an angle 0 between tip 12a of restraining pawl 12and notched portion 11a of restraining plate 11 as shown in FIG. 3b andsimultaneously with the termination of cocking both members engage witheach other to be restrained thereby.

Rear screen disk 18, rear screen cylinder 20 the circumferential edgethereof to which one end of rear screen B is pasted, and rear screenrestraining plate 21 are fixed to second wind-up shaft 17. Further,, onthe upper and lower sides of rear screen cylinder 20 guide rollers 19and 19' for guiding front screen ribbon A, are fitted loosly.

Rear screen restraining plate 21 is provided with notched portion 21aand supported by a pin on the base plate of the camera body andengageable with rear screen restraining pawl 22. And just before shuttercocking is terminated restraining pawl 22 engages with restraining plate21 as shown in FIG. 3a.

Front and rear screen driving springs are disposed nearly symmetricallyto the take-up shaft on the opposite side to first and second wind-upshafts 9 and 17 relative to the optical axis of FIG. 1, and from screendriving spring 26 is fixed to front screen spring shaft 23 at one end26a thereof and the other end 26b thereof is fixed to a portion of frontscreen cylinder 25 fitted rotatably on spring shaft 23 and pasted withthe tip of front screen A Spring 26 is contained in cylinder 25.

Upper and lower ends 23a and 23b of front screen spring shaft 23 aresupported respectively by a pin on the base plate of the camera body,and on the upper and lower sides of front screen cylinder 25 guiderollers 24 and 24' for guiding rear screen ribbon B are fitted loosely.Near the upper end 23a ratchet wheel 27 is fixed so as to check thecounterclockwise rotation of spring shaft 23 by means of ratchet 27.And, by means of ratchet wheel 27 and ratchet 28 it is possible tomoderate the required front screen driving force by adjusting theinitial number of winding.

Rear screen spring 31 is fixed at one end thereof to a portion of rearscreen spring disk 30 fixed to rear screen spring shaft 29 and the otherend thereof is fixed to ratchet 32 fitted loosely on spring shaft 29 andmore fully described below.

Rear screen spring shaft 29 is supported at upper and lower ends 29a and29b thereof by pins on the base plate of the camera body, and to theupper and lower portions of spring shaft 29 rear screen spring disks 30and 30' are fixed respectively. On the circumferential edges of disks 30and 30' the tip of rear screen ribbon B is pasted. And, ratchet wheel 32is arranged to engage with ratchet 33 supported by a pin on intermediatebase plate 34 fitted loosely on spring shaft 29 to check ratchet wheel33 from rotating counterclockwise.

Rear screen spring 31 fitted on rear screen spring shaft 29 is fixed atone end thereof onto rear screen spring disk 30 and at the other endthereof onto a portion of ratchet wheel 33 to rotate spring shaft 29clockwise so as to energize it.

Therefore, opening screen cylinder 25 to which front screen A is pastedand rear screen spring disks 30 and 30' to which rear screen ribbon B,is pasted are ordinarily rotated clockwise to be energized andaccordingly front and rear shutter screens A, and B are arranged to moveto the right in front of exposure opening frame 35.

And, the structure is so arranged that the inertias of movement of thefront and rear screens, namely, the inertias of first wind-up shaft 9and front screen cylinders 10 and 10 are equal to the inertias of rearscreen spring shaft 29 and rear screen spring disks 30 and 30. Theinertias of front screen guide rollers 19 and 19' are equal to theinertias of rear screen guide rollers 24 and 24'. The inertia of frontscreen spring cylinder 25 is equal to the inertias of second wind-upshaft 17 and rear screen cylinder 20. Finally, the inertia of frontscreen restraining plate 11 is equal to the inertia of rear screenrestraining plate 21.

Since the present invention is constructed as described above, uponturning the film winding lever, driving gear 1 interlocked therewith isrotated counterclockwise and connection gear 2 meshed with driving gear1 is rotated clockwise, thereby over energizing return spring 4.Simultaneously therewith, front and rear screen gears 5 and 13 meshedrespectively with said connection gear 2 and driving plates 6 and 14fixed in a body respectively with screen gears 5 and 13, also arerotated counterclockwise using bearing rings 7 and 15 respectively as acenter.

At this juncture, since driving pins 6a and 14a on driving plates 6 and14 move in the energizing direction counterclockwise free ends 8a and16a of springs 8 and 16 fitted respectively onbearing rings 7 and 15.Free ends 8a and 16a come into contact respectively with screen shaftpins 10a and 18a provided respectively on front screen cylinder 10 andrear screen disk 18 fixed in a body respectively with first and secondwind-up shafts 9 and 17 so as to rotate shafts 9 and 17counterclockwise. As a result, front screen ribbon A pasted on thecircumferential edges of front screen cylinders 10 and 10' is led byfront screen guide rollers 19 and 19' fitted loosely on second wind-upshaft 17 to move front screen A, to the left. Therefore, front screenspring cylinder 25 with front screen A is rotated counterclockwise aboutfront screen spring shaft 23 as a center to energize front screendriving spring 26 accommodated in spring cylinder 25. And, with theprogress of rotation of second windvup shaft 17 rear screen cylinderfixed thereto is rotated counterclockwise. Therefore, rear screen 8, onscreen cylinder 20 is wound to move to the left along with rear screenribbon 8,. Since rear screen ribbon B led by rear screen guide rollers24 and 24' fitted loosely on front screen spring shaft 23 is pasted onrear screen spring disks 30 and 30' fixed in a body with front screenspring shaft 29, it energizes rear screen driving spring 31simultaneously with the driving of the rear screen.

At this juncture, the positions of the edge end of the front and rearscreens are as shown in FIG. 2 and rear edge A, of the front screen isadvanced to the left by a distance X from front edge B of rear screenand the screen overlap quantity required to screen the light ismaintained.

And, just before winding is terminated front and rear screen restrainingplates 1 l and 21 fixed respectively to first and second wind-up shafts9 and 17 hold the relative position as shown in FIG. 3b. Rear screenrestraining plate 21 is in a position where notch 21a thereof engageswith hook 22a of rear screen restraining pawl 22, and in the meantimefront screen restraining plate 11 is in a position where the frontscreen is wound up excessively by an angle 9 equivalent to the screenoverlap portion X from the engage position of tip 12a of front screenrestraining pawl 12.

Then, upon reaching the winding state, as shown in FIG. 4 toothlessportion la of driving gear 1 is rotated to mesh with connection gear 2and accordingly driving gear 1 is disengaged from connection gear 2, andconnection gear 2 starts to be rotated counterclockwise to return byvirtue of the force of return spring 4. And, at the same time front andrear screen gears 5 and 13 meshed with connection gear 2 are rotatedclockwise as shown by the arrows in FIG. 4, being accompanied by drivingplates 6 and 14 fixed in a body therewith and accordingly springs 8 and18 in contact with fixed driving pins 6a and 14a also follow ininterlocking therewith via free ends 8a and 16a.

Then, front and rear screen cylinders 10 and 20 are disconnectedrespectively from free ends 8a and 16a and front and rear screen shaftpins 10a and 18a follow in relationship therewith clockwise also by theforce of front and rear driving springs 26 and 31 respectively. However,in the case of rear screen B notch 21a of restraining plate 21 engageswith restraining pawl 22 so that the running movement of the rear screenis checked.

However, front screen A: is wound up excessively by an angle 6 from theengage position of tip 12a of front screen restraining pawl 12 alongnotch 11a of front screen restraining plate 11 and accordingly unwindsfollowing after the reverse of front screen gear 5 until restrainingplate 11 is meshed with restraining pawl 12 by the front of screendriving spring 26. Thereby, front screen A is moved alone by a distanceX to the right and positions of the rear edge A of front screen andfront edge 13;, of rear screen coincide with each other.

Subsequently, the reverse and return of connection gear 2 takes placeand at a position where connection gear 2 is rotated through about ahalf revolution front and rear screen gears 5 and 13 and driving plates6 and 14 fixed thereto are arranged to rotate through about onerevolution, so that driving pins 6a and 14a and screen shaft pins 10aand 18a ar respectively arranged nearly on one straight line relative tofirst and second wind-up shafts 9 and 17. Free ends 8a and 16a of spring8 and 16 which come to this position following the contact andinterlocking with driving pins 6a and 14a come into contact with theopposite side of screen shaft pins 10a and 18a in the positions shown inFIG. 2 to be restrained and disconnected from driving pins 6a and 14a.

Thereafter, connection gear 2 continues a counterclockwise rotation onlyby means of the force of return spring 4. Therefore, front and rearscreen gears 5 and 13 and driving plates 6 and 14 start the secondrevolution and at last as shown in FIG. 4 pin 2a on connection gear 2runs against fixed stop plate 35 shown by a one point chain line in FIG.4 to terminate the reverse return movement. At this juncture, drivingpins 6a and 14a fixed in a body with front and rear screen gears and 13are positioned before coming into contact with free ends 8a and 16a ofsprings 8 and 16 as shown in FIG. 6.

Next, upon depressing the release button, not shown in the drawings,front screen restraining pawl 12 is rotated clockwise as shown in FIG.5b and tip 12a thereof comes out of notch 12a of front screenrestraining plate 11 to release the front screen. Therefore, frontscreen A moves to the right by the force of front screen driving spring26 and spring 8 via front screen guide rollers 19 and 19', accompaniedby the rotation of first windup shaft 9, and front screen cylinders and10' and front screen restraining plate 11. Thereby an exposure to a filmaccommodated in the rear of exposure opening frame 35 is made.

After the movement of the front screen is started, when the timerequired elapses hook 22a of rear screen restraining pawl 22 isretreated to rotate from notch 21a of rear screen restraining plate 21by the action of a well-known governor gear omitted in the embodimentand releases the rear screen. Therefore, rear 7 screen B runs to theright in the same way as the front screen by the force of rear screendriving spring 31 and spring 16 along with the rotation of rear screencylinder 20 and rear screen restraining plate 21. Thereby, the exposureto of the film is terminated.

In the process of the shutter movement, springs 8 and 16 for have freeends 8a and 16a engaged with driving pins 6a and 14a to push them andpromote shutter movement during about one revolution from the startingof front and rear screen cylinders 10 and 20. However, after ends 8a and16a engage with the opposite side of driving pins 6a and 14a to stop,front and rear shutter screens A and B are driven only by means of theforce of front and rear screen driving springs 26 and 31. Front screencylinder 10 and rear screen disk 18 are rotated through about tworevolutions from their starting point, and screen shaft pins 10a and 18arun against free ends 8a and 16a to terminate the movement of theshutter. The positions of the components at this juncture are shown inFIG. 7 and the impact force accompanied by the stopping of the shutteris absorbed by an elastic deformation of free ends 80 and 16 a ofsprings 8 and 16. The front edge of the rear screen is advanced to theright by a distance X as shown in FIG. 7 as compared with the rear edgeof front screen and the screen overlap required to screen the light isobtained.

In connection with FIG. 8 and FIG. 9 the construction of the secondembodiment in accordance with the present invention will be describedhereinafter.

Driving gear 101 interlocks with a winding lever not shown in thedrawings and is provided with toothless portion 101a which disconnectswith connection gear 102 which meshes with winding gear 101 just aftertermination of winding.

Connection gear 102 is pivotted rotatably on fixed shaft 103 on baseplate 138 of the camera body and on the top surface of gear 102 pin 102ais mounted. And, onto pin 102a is suspended one end 104 of return spring104 wound round fixed shaft 103.

Front and rear screen gears 105 and 113 mesh with connection gear 102 toconstitute a speed up gear train and are fitted loosely on first andsecond wing-up shafts 109 and 117 respectively. And, onto gears 106 and114 front and rear screen driving plates are respectively fixed and onthe projection piece portions of both plates 106 and 104 driving pins106a and 114a are provided.

The upper and lower ends of first and second windup shafts 109 and 117are supported respectively on bearing portions 10%, 109b and 117b, 117'bof base plates 138 and 138' of the camera body. At respective positionson shaft 109 and 117 control screws (righthand screws) 109a and 117a arerespectively threaded, with which front and rearscreen control nuts 107and are coupled. ln fork portions 108a and 116a of control plates 108and 116 fixed to nuts 107 and 115, driving pins 106a and 114a are fittedrespectively to engage with each other and also engage respectively withfront and rear screen shaft pins 110a and 118a mounted respectively onfront screen cylinder 110 and rear screen disk 1 18 described below. Asshown in FIG. 9d driving pins 106a and 114a engage with shaft pins 11aand 118a respectively and cooperate respectively with each other incontacting with each other also during winding. And, the engagingrelation of both pins is so arranged that they are engaged or disengagedby going up and down through about one revolution of both control plates108 and 116.

Further, to first wind-up shaft 109 there are fixed front screencylinders 110 and 110 on which circumferential edge front screen ribbonA, is pasted, and front screen restraining plate 111. And, front screenrestraining plate 111 is provided with notch 111a and engageable withpawl 112a of front screen restraining lever 112 supported by a pin onbase plate 138' of the camera body and rotatable in interlocking withthe release operation. Restraining lever 112 and pawl 112a are formed toengage with each other to be restrained at the termination of winding.

And, to second wind-up shaft 117 there are fixed rear screen disk 118,rear screen cylinder 120, on which circumferential edge one end of rearscreen B is pasted, and rear screen restraining plate 121. And on theupper and lower sides of rear screen cylinder 120 guide rollers 119 and119 for guiding front ribbon A are respectively fitted loosely. And,rear screen restraining plate 121 is provided with notch 121a andengageable with pawl 122a of rear screen restraining lever 122 supportedby a pin on base plate 138 of the camera body and rotatable ininterlocking with the release operation and so formed as to engage to berestrained at the termination of winding.

In addition, front screen ribbon A, is connected with front screen A viafront screen rear edge plate 135, and rear screen B is connected withclosing screen ribbon 13 via rear screen front edge plate 136, and it isunderstood that screens A and B are formed to move always to the rightby a well-known driving means not shown in the drawings.

Since the second embodiment is constructed as described above, uponturning the winding lever driving gear 101 interlocked therewith isrotated in the direction shown by the arrow (counterclockwise) andaccordingly connection gear 102 meshed with driving gear 101 is rotatedin the direction shown by the arrow (clockwise) thereby over energizingreturn spring 104, using fixed shaft 103 as a center via pin 102a ongear 102. Front and rear screen gears 105 and 113 meshed with gear 102are rotated, front and rear screen driving plates 106 and 114 fixed in abody respectively with gears 105 and 113, and driving pins 106a and 114amounted respectively on driving plates 106 and 114 are rotated in thedirection shown by the arrow (counterclockwise). Therefore, front andrear screen control plates 108 and 116 for engaging respectively withdriving pins 106a and 114a and front and rear screen control nuts 107and 115 fixed in a body respectively with control plates 108 and 116 arerotated in the same direction (counterclockwise). And thereby bothscreen shaft pins 110a and 118a in contacting respectively with the endportions of front and rear screen control plates 108 and 116 are movedand accordingly a counterclockwise rotation is given to first and secondwindup shafts 109 and 117 to which front screen cylinder 110 and rearscreen disk 118 having shaft pins 110a and 118a mounted thereon arerespectively fixed.

Therefore, front and rear screen cylinders 111, 110, and 119 fixed in abody respectively to first and second wind-up shafts 109 and 117 alsoare rotated counterclockwise to wind up front and rear screens A and BRestraining pawls 112a and 122a engage respectively with front and rearscreen restraining plates 111 and 121 to terminate winding. (See FIG.9a).

Upon termination of winding, toothless portion 101a of driving gear 101meshes with connection gear 102 and thereby the connections with bothgears 101 and 102 are broken off, and connection gear 102 and first andsecond wind-up gears 105 and 113 are reversed to return by the force ofreturn spring 104. And at the same time front and rear screen controlplates 108 and 116 and control nuts 107 and 115 also are reversed in thesame direction via driving pins 106a and 114a on front and rear screendriving plates 106 and 114 fixed respectively to first and secondwind-up gears 105 and At this juncture, since first and second wind-upshafts 109 and 117 are respectively restrained by front and rearrestraining pawls 112a and 122a, with the clockwise rotation of frontand rear screen control nuts 107 and 115. Thereby control nuts 107 and115 are control plates 108 and 116 can come down, and on the returningmotion where about one revolution is effected, as shown in FIG. 98,front and rear shaft pins 110a and 1180, and front and rear controlplates 108 and 116 start to come down from the engage position wherefront and rear screen shaft pins 110a and 118a come into contactrespectively with front and rear screen control plates 108 and 116.Thereby, further returning rotation is continued and the return isterminated at the winding start position shown in FIG. 9c.

Then, upon depressing the release button, through the rotation of frontscreen restraining lever 112 interlocked with the release button, frontscreen restraining plate 111 is released and accordingly first wind-upshaft 109 and front screen cylinders 110 and 110' start to rotateclockwise in a body. And successively, by means of a well-known governorgear or an electric time delay circuit rear screen restraining lever 122releases rear screen restraining plate 112 and second wind-up shaft 117and rear screen disk 119 are rotated clockwise in a body.

At this juncture, front and rear screen control plates 108 and 116 andcontrol nuts 107 and 115 are fixed via front and rear screen drivingpins 106a and 114a fixed 6 control plates 108 and 116 come up, and whenfront and rear screen cylinder 110 and 119 come to the stop positionfront and rear screen shaft pins 1 10a and 118a come into contactrespectively with front and rear screen control plates 108 and 116 whichhave moved up. Shutter screens A and B are stopped and take the positionshown in FIG. 9d.

I And, front and rear screen shaft pins 110a and 118a are in contactrespectively with front and rear screen control plates 108 and 116, andthen simultaneously with winding, first and second wind-up gears and113, front and rear screen driving pins 106a and 114a, front and rearscreen control plates 108 and 116, and first and second wind-up shafts107 and 119 also are rotated together with. Therefore, when winding isterminated the components return to the position shown in FIG. 9a.

Since the second embodiment is constructed as described above, bylengthening the control screw the rotation angle of the screen cylindercan be enlarged, and provided that the shutter screen running distanceis L, the screen cylinder radius of R, and the rotation angle of thescreen cylinder is 6, R-9=L, and the inertia of the screen cylinder isproportional to R. Therefore, when the rotation angle 9 of the screencylinder is enlarged, R becomes smaller and accordingly the inertiathereof can be decreased.

1 claim:

1. A focal plane shutter control mechanism for a camera having front andrear screens respectively biased to be driven from cocked positions torest positions, a first retaining member for retaining said front screenin said cocked position, a second retaining member for retaining saidrear screen in said cocked position, a first wind-up shaft for windingsaid front screen, and a second wind-up shaft for winding said rearscreen, comprising:

driving means rotatable in response to shutter wind up operation; firstand second wind-up gears; transmission means for driving said first andsecond wind-up gears in shutter wind-up directions in re sponse to themovement of said driving means;

first means for interconnecting said first wind-up shaft with said firstwind-up gear when said first wind-up gear is driven in the shutterwind-up direction;

second means for interconnecting said second windup shaft with saidsecond wind-up gear when said second wind-up gear is driven in theshutter windup direction;

said driving means including means for disengaging said transmissionmeans therefrom when said front and rear screens are in said cockedpositions, and said transmission means being biased to return to a restposition with said wind-up gears when said driving means disengages saidtransmission means therefrom;

said first means disconnecting said first wind-up gear from said firstwind-up shaftwhen said first windup gear is driven in a directionopposite to said shutter wind-up direction; and

said second means disconnecting said second windup gear from said secondwind-up shaft when said second wind-up gear is driven in a directionopposite to said shutter wind-up direction.

2. A focal plane shutter control mechanism as claim 1, wherein saiddriving means is a gear and said means for disengaging is a non-toothedsegment thereof.

3. A focal plane shutter control mechanism as in claim 2, wherein saidfront and rear screens in said cocked positions partially overlap witheach other, and further comprising means for compensating said partialoverlap when said first and second screens are released for an exposure.

4. A focal plane shutter control mechanism as in claim 3, furthercomprising a first cam member mounted on said first wind-up shaft torotate therewith and engageable with said first retaining member, and asecond cam member mounted on said second wind-up shaft to rotatetherewith and engageable with said second retaining member, said firstcam member is rotatable beyond the position to be engaged by said firstretaining member with said second cam member rotating to the position tobe engaged by said second retaining member whereby said first cam memberis returned through the bias for the first screen until said first cammember engages with said first retaining member thereby compensating forsaid overlap when said first wind-up gear is disconnected from saidfirst wind-up shaft.

5. A focal plane shutter control mechanism as in claim 3, wherein saidfirst and second means each comprises a first pin respectively rotatablewith said first and second wind-up gear, a second pin respectivelyrotatable with said first and second wind-up shaft, and a coil springenergized in the direction opposite to said shutter wind-up direction ofsaid first or second windup gears, and said coil spring having anextension for engaging said first and second pins whereby said first pindrives said second pin by means of said coil spring when said first orsecond wind-up gear is driven in the shutter wind-up direction.

6. A focal plane. shutter control mechanism as in claim 5, wherein thegear ratioof said transmission means and said first wind-up gear and thegear ratio of said transmission means and said second wind-up gear areso selected that both said first and second wind-up gears rotate morethan one revolution until said transmission means rotates to said restposition, whereby said coil springs also drive said front and rearscreens.

7. A focal plane shutter control mechanism as in claim 4, wherein eachof said first and second means comprises a first pin respectivelyrotatable with said first and second wind-up gear, a second pinrespectively rotatable with said first and second wind-up shaft, anintermediate member having a slot to receive said first pin, and meansfor moving said intermediate member in accordance with the relativemovement of said first or second wind-up shaft and with said first orsecond wind-up gear whereby said intermediate member is engageable withsaid second pin with said first or second wind-up gear driven in theshutter wind-up direction and disengaged from said second pin with saidfirst or second wind-up gear driven in the reverse direction.

8. A focal plane shutter control mechanism as in claim 7, wherein saidmeans for moving comprises a threaded portion formed on said first andsecond windup shafts, and an internally threaded bore formed in saidintermediate member and engaging said threaded portion.

9. A focal plane shutter control mechanism as in claim 1, wherein saidfirst and second means each comprises a first pin respectively rotatablewith said first and second wind-up gear, a second pin respectivelyrotatable with said first and second wind-up shaft, and a coil springenergized in the direction opposite to said shutter wind-up direction ofsaid first or second windup gears, and said coil spring having anextension for engaging said first and second pins whereby said first pindrives said second pin by means of said coil spring when said first orsecond wind-up gear is driven in the shutter wind-up direction.

10. A focal plane shutter control mechanism as in claim 9, wherein thegear ratio of said transmission means and said first wind-up gear andthe gear ratio of said transmission means and said second wind-up gearare so selected that both said first and second wind-up gears rotatemore than one revolution until said transmission means rotates to saidrest position, whereby said coil springs also drive said front and rearscreens.

11. A focal plane shutter control mechanism as in claim 1, wherein eachof said first and second means comprises a first pin respectivelyrotatable with said first and second wind-up gear, a second pinrespectively rotatable with said first and second wind-up shaft, anintermediate member having a slot to receive said first pin, and meansfor moving said intermediate member in accordance with the relativemovement of said first or second wind-up shaft and with said first orsecond wind-up gear whereby said intermediate member is engageable withsaid second pin with said first or second wind-up gear driven in theshutter wind-up direction and disengaged from said second pin with saidfirst or second wind-up gear driven in the reverse direction.

12. A focal plane shutter control mechanism as in claim 11, wherein saidmeans for moving comprises a threaded portion formed on said first andsecond windup shafts, and an internally threaded bore formed in saidintermediate member and engaging said threaded portion.

13. A focal plane shutter control mechanism as in claim 1, wherein theinertia of said front screen and members driven with the front screen isapproximately equal to that of said rear screen and members driven withsaid rear screen.

14. A focal plane shutter control mechanism as in claim 13, furthercomprising winding members around which a respective one end of saidfront screen and said rear screen is wound, the other end of said frontand rear screen is respectively wound around respective ones of saidfirst and second wind-up shafts and rotatable with respect to each ofsaid first and second windup shafts; and rotatable biasing means betweensaid first and second wind-up shafts and said winding members to driverespectively said front and rear screens to said rest positions fromsaid cocked positions relative to said first and second wind-up shafts;and at least one of said first or second wind-up shafts is rotatable andthe rotating position thereof is fixed adjustably to said winding memberin the rest position thereof.

1. A focal plane shutter control mechanism for a camera having front andrear screens respectively biased to be driven from cocked positions torest positions, a first retaining member for retaining said front screenin said cocked position, a second retaining member for retaining saidrear screen in said cocked position, a first wind-up shaft for windingsaid front screen, and a second wind-up shaft for winding said rearscreen, comprising: driving means rotatable in response to shutterwind-up operation; first and second wind-up gears; transmission meansfor driving said first and second wind-up gears in shutter wind-updirections in response to the movement of said driving means; firstmeans for interconnecting said first wind-up shaft with said firstwind-up gear when said first wind-up gear is driven in the shutterwind-up direction; second means for interconnecting said second wind-upshaft with said second wind-up gear when said second wind-up gear isdriven in the shutter wind-up direction; said driving means includingmeans for disengaging said transmission means therefrom when said frontand rear screens are in said cocked positions, and said transmissionmeans being biased to return to a rest position with said wind-up gearswhen said driving means Disengages said transmission means therefrom;said first means disconnecting said first wind-up gear from said firstwind-up shaft when said first wind-up gear is driven in a directionopposite to said shutter wind-up direction; and said second meansdisconnecting said second wind-up gear from said second wind-up shaftwhen said second wind-up gear is driven in a direction opposite to saidshutter wind-up direction.
 2. A focal plane shutter control mechanism asclaim 1, wherein said driving means is a gear and said means fordisengaging is a non-toothed segment thereof.
 3. A focal plane shuttercontrol mechanism as in claim 2, wherein said front and rear screens insaid cocked positions partially overlap with each other, and furthercomprising means for compensating said partial overlap when said firstand second screens are released for an exposure.
 4. A focal planeshutter control mechanism as in claim 3, further comprising a first cammember mounted on said first wind-up shaft to rotate therewith andengageable with said first retaining member, and a second cam membermounted on said second wind-up shaft to rotate therewith and engageablewith said second retaining member, said first cam member is rotatablebeyond the position to be engaged by said first retaining member withsaid second cam member rotating to the position to be engaged by saidsecond retaining member whereby said first cam member is returnedthrough the bias for the first screen until said first cam memberengages with said first retaining member thereby compensating for saidoverlap when said first wind-up gear is disconnected from said firstwind-up shaft.
 5. A focal plane shutter control mechanism as in claim 3,wherein said first and second means each comprises a first pinrespectively rotatable with said first and second wind-up gear, a secondpin respectively rotatable with said first and second wind-up shaft, anda coil spring energized in the direction opposite to said shutterwind-up direction of said first or second wind-up gears, and said coilspring having an extension for engaging said first and second pinswhereby said first pin drives said second pin by means of said coilspring when said first or second wind-up gear is driven in the shutterwind-up direction.
 6. A focal plane shutter control mechanism as inclaim 5, wherein the gear ratio of said transmission means and saidfirst wind-up gear and the gear ratio of said transmission means andsaid second wind-up gear are so selected that both said first and secondwind-up gears rotate more than one revolution until said transmissionmeans rotates to said rest position, whereby said coil springs alsodrive said front and rear screens.
 7. A focal plane shutter controlmechanism as in claim 4, wherein each of said first and second meanscomprises a first pin respectively rotatable with said first and secondwind-up gear, a second pin respectively rotatable with said first andsecond wind-up shaft, an intermediate member having a slot to receivesaid first pin, and means for moving said intermediate member inaccordance with the relative movement of said first or second wind-upshaft and with said first or second wind-up gear whereby saidintermediate member is engageable with said second pin with said firstor second wind-up gear driven in the shutter wind-up direction anddisengaged from said second pin with said first or second wind-up geardriven in the reverse direction.
 8. A focal plane shutter controlmechanism as in claim 7, wherein said means for moving comprises athreaded portion formed on said first and second wind-up shafts, and aninternally threaded bore formed in said intermediate member and engagingsaid threaded portion.
 9. A focal plane shutter control mechanism as inclaim 1, wherein said first and second means each comprises a first pinrespectively rotatable with said first and second wind-up gear, a secondpin respectively rotatable with said first and second wind-up shaft, anda coil spring enErgized in the direction opposite to said shutterwind-up direction of said first or second wind-up gears, and said coilspring having an extension for engaging said first and second pinswhereby said first pin drives said second pin by means of said coilspring when said first or second wind-up gear is driven in the shutterwind-up direction.
 10. A focal plane shutter control mechanism as inclaim 9, wherein the gear ratio of said transmission means and saidfirst wind-up gear and the gear ratio of said transmission means andsaid second wind-up gear are so selected that both said first and secondwind-up gears rotate more than one revolution until said transmissionmeans rotates to said rest position, whereby said coil springs alsodrive said front and rear screens.
 11. A focal plane shutter controlmechanism as in claim 1, wherein each of said first and second meanscomprises a first pin respectively rotatable with said first and secondwind-up gear, a second pin respectively rotatable with said first andsecond wind-up shaft, an intermediate member having a slot to receivesaid first pin, and means for moving said intermediate member inaccordance with the relative movement of said first or second wind-upshaft and with said first or second wind-up gear whereby saidintermediate member is engageable with said second pin with said firstor second wind-up gear driven in the shutter wind-up direction anddisengaged from said second pin with said first or second wind-up geardriven in the reverse direction.
 12. A focal plane shutter controlmechanism as in claim 11, wherein said means for moving comprises athreaded portion formed on said first and second wind-up shafts, and aninternally threaded bore formed in said intermediate member and engagingsaid threaded portion.
 13. A focal plane shutter control mechanism as inclaim 1, wherein the inertia of said front screen and members drivenwith the front screen is approximately equal to that of said rear screenand members driven with said rear screen.
 14. A focal plane shuttercontrol mechanism as in claim 13, further comprising winding membersaround which a respective one end of said front screen and said rearscreen is wound, the other end of said front and rear screen isrespectively wound around respective ones of said first and secondwind-up shafts and rotatable with respect to each of said first andsecond wind-up shafts; and rotatable biasing means between said firstand second wind-up shafts and said winding members to drive respectivelysaid front and rear screens to said rest positions from said cockedpositions relative to said first and second wind-up shafts; and at leastone of said first or second wind-up shafts is rotatable and the rotatingposition thereof is fixed adjustably to said winding member in the restposition thereof.